This invention relates to polyether-based, urethane-group-containing polyamines which contain polymers and/or copolymers of unsaturated compounds, preferably in the form of graft polymers, and optionally urea and/or biuret and/or allophanate groups. The invention also relates to a process for the production of such polyamines by the hydrolysis of NCO-prepolymers containing terminal isocyanate groups.
Polyamines containing urethane groups are known to those in the art. German Auslegeschrift No. 1,270,046 for example, describes a process for the production of specific primary aromatic amines containing polyalkylene glycol ether segments in which reaction products of aromatic diisocyanates or triisocyanates with polyalkylene glycol ethers and/or polyalkylene glycol thioethers are reacted with secondary or tertiary carbinols. The products of this reaction are subsequently subjected (optionally in the presence of acid catalysts) to thermal decomposition in an inert solvent. One of the disadvantages of this process is that thermal decomposition of the urethanes is accompanied by formation of combustible, readily volatile alkenes which are explosive in admixture with air. Precautionary measures must therefore be taken.
German Auslegeschrift No. 1,694,152 relates to the production of prepolymers containing at least two terminal amino groups by reacting hydrazine, aminophenyl ethyl amine or other diamines with an NCO-prepolymer of a polyether polyol and a polyisocyanate (NCO/NH-ratio=1:1.5 to 1:5). In this process, unreacted amine has to be carefully removed in an additional step because it catalyzes the reaction with polyisocyanates to a considerable extent (thus leading to short processing times) and may act as a reactant.
Another process for synthesizing polyamines containing urethane groups is described in French Pat. No. 1,415,317. In this process, NCO-prepolymers containing urethane groups are converted with formic acid into the N-formal derivatives which are then hydrolyzed to form terminal aromatic amines. The reaction of NCO-prepolymers with sulfamic acid in accordance with German Auslegeschrift No. 1 155 907 (U.S. Pat. No. 3,184,502) also gives compounds containing terminal amino groups. Relatively high molecular weight, prepolymers containing aliphatic secondary and primary amino groups are obtained in German Auslegeschrift No. 1,215,373 by reacting hydroxyl compounds of relatively high molecular weight with ammonia in the presence of catalysts under pressure at elevated temperatures. Such prepolymers are made in U.S. Pat. No. 3,044,989, by reacting polyhydroxyl compounds of relatively high molecular weight with acrylonitrile followed by catalytic hydrogenation. According to German Offenlegungsschrift No. 2,546,536 and U.S. Pat. No. 3,865,791, relatively high molecular weight compounds containing terminal amino groups and urethane groups are also obtained by reacting NCO-prepolymers with enamines, aldimines or ketimines containing hydroxyl groups, followed by hydrolysis.
It is known that aromatic isocyanates can be converted into primary amines by acid hydrolysis. However, the reaction is far from complete because the amine formed during hydrolysis reacts further with unreacted isocyanate to form the corresponding urea. This further reaction cannot be suppressed even by using excess strong mineral acid. (See, e.g., Japanese Patent No. 55007-825).
It is also known that polyurethanes which have been produced from so-called polymer polyols, which are polyether polyols graft-modified by polymers or copolymers of olefinically unsaturated monomers, are distinguished by an improved property level. In particular, the hardness and durability of flexible polyurethane foams is favorably affected so that low unit weights can be adjusted and savings made on raw materials. Additionally, these polymer polyols provide flexible foams with more open cells and, as a result, counteract shrinkage of fresh foams during storage. Finally, it is possible to use polymer polyols (provided that the basic polyether is suitably selected) to produce so-called highly elastic, cold-hardening foams. In contrast to conventional processes for the production of foams of this type, there is no need to use special polyisocyanates characterized by balanced reactivity. It is therefore possible to use standard commercial products, particularly the tolylene diisocyanate used predominantly in the manufacture of flexible foams.